Methods that implement high-sensitivity and low-level analyte detection in conjunction with rapid and reproducible experimental protocols are the cornerstone of modern analytical measurements. Currently, most known techniques for quantifying low levels of target analyte in a sample matrix use amplification procedures to increase the number of reporter molecules and thereby provide a measurable signal. These known processes include enzyme-linked immunosorbent assays (ELISA) for amplifying the signal in antibody-based assays, as well as the polymerase chain reaction (RCA) for amplifying target DNA strands in DNA-based assays. A more sensitive but indirect protein target amplification technique, called immuno-RCA (see Sano, T.; Smith, C. L.; Cantor, C. R. Science 1992, 258, 120-122), makes use of oligonucleotide markers, which can subsequently be amplified using PCR and detected using a DNA assay (see Nam, J. M.; Thaxton, C. S.; Mirkin, C. A. Science 2003, 301, 1884-1886; Niemeyer, C. M.; Adler, M.; Pignataro, B.; Lenhert, S.; Gao, S.; Chi, L. F.; Fuchs, H.; Blohm, D. Nucleic Acids Research 1999, 27, 4553-4561; and Zhou, H.; Fisher, R. J.; Papas, T. S. Nucleic Acids Research 1993, 21, 6038-6039). While the immuno-PCR method permits ultra low-level protein detection, it is a complex assay procedure, and can be prone to false-positive signal generation (see Niemeyer, C. M.; Adler, M.; Wacker, R. Trends in Biotechnology 2005, 23, 208-216).
One disadvantage of these known methods is their reliance on separate steps to amplify reporter molecules to provide a measurable signal, thereby requiring additional amplification steps and thus additional time, equipment, and materials.
In addition, known methods for accurately quantifying the concentration of a particular analyte in solution are all based on ensemble responses in which many analyte molecules give rise to the measured signal.
Therefore, there is a need in the art for an improved method and system of target analyte detection.